Question

Consider the code below

class Pin
{
   string Name; //can be either Numerical or AlphaNum
}

enum Place
{
    Left,
    Right
}

class Map
{
   Pin pin;
   Place Place;
   Rectangle Rect;
}

The Pin‘s Name field can be only numerical or alphanumerical, so I went by string to support both.

Now My quesion is if I have a List<Map> how can I sort this list by Pin’s Name field? I tried the code below but it can’t compile:

map.Sort((x, y) => x.Pin.Name.CompareTo(y.Pin.Name)); 
//Cannot implicitly convert type 'void' to 'System.Collections.Generic.List<DataModels.PinMap>

Answer 1

The code you showed doesn’t produce that compiler error. I assume that you are trying to assign the result to a new variable or to itself. Something like this:

map = map.Sort(...);

That’s not possible or necessary as List<T>.Sort is doing an in-place sort, i.e. it changes the original list and therefore doesn’t return anything. So, simply removing the assignment should make the compiler error go away.

If you don’t want an in-place sort, simply use Enumerable.OrderBy in combination with ToList to produce a new list:

var result = map.OrderBy(x => x.pin.Name).ToList();